Computed tomography and ultrasound in parapneumonic effusions and empyema.

AIM: Imaging of pleural empyema by ultrasound (US) or computed tomography (CT) is used to confirm the diagnosis and facilitate drainage. However, the information gained from US and CT may also have prognostic significance. The aim of the present study was to determine if CT and US appearances correlated with the severity of infection as determined by established microbiological and biochemical indicators, and to establish whether either technique could predict those patients who will fail drainage and require surgery. MATERIALS AND METHODS: Fifty patients with parapneumonic effusions were assessed. All had thoracic CT and the results of thoracic US were available in 36 patients. Imaging features were compared to the stage of the effusion and clinical outcome. RESULTS: At US, 7/36 (19%) pleural collections were anechoic, 5/36 (14%) were hyperechoic without septae and 24/36 (67%) were hyperechoic with septae. There was no relationship between US appearances and the presence of pus, the effusion stage or the need for surgical treatment. On CT pleural enhancement was seen in all patients. There was evidence of pleural thickening in 46/50 (92%) and thickening of extrapleural fat in 38/50 (76%). There was a trend for mean pleural thickness to increase with an increasing stage of pleural infection. However, a wide range of appearances were seen and overall the thickness of pleural/extrapleural tissues was not significantly related to the stage of effusion or to the requirement for surgery. CONCLUSIONS: Although US and CT have established roles in the investigation of parapneumonic effusions, neither technique reliably identifies the stage of pleural infection or predicts those patients who subsequently require surgical intervention after failed management by chest tube drainage and intrapleural fibrinolytics. Kearney, S. E. (2000). Clinical Radiology 55, 542-547.

The characteristics and significance of thoracic lymphadenopathy in parapneumonic effusion and empyema.

The occurrence of significant mediastinal lymphadenopathy together with pleural effusion or empyema inevitably raises concern about the presence of intrathoracic malignancy or granulomatous disease. Lymph node enlargement may also occur when pneumonia is accompanied by a parapneumonic effusion or empyema. Features that allow "benign" lymph node enlargement to be distinguished from malignant causes have not previously been determined. The present study aims to establish the CT characteristics of enlarged nodes in parapneumonic effusion. The appearances of mediastinal lymph nodes were recorded in 50 consecutive patients with parapneumonic effusion/empyema. 18 (36%) had mediastinal lymphadenopathy (node size greater than 1 cm). The mean number of enlarged nodes was 1.9 (range 1-3) and the mean size was 1.4 cm (2 cm maximum). Seven patients had a single involved site, nine patients two sites and two patients three sites. The right paratracheal area was most commonly involved and the subcarinal area contained the largest nodes. The presence of enlarged nodes did not correlate with biochemical and microbiological stage of pleural infection, length of history, or extent of consolidation. This study shows that mediastinal lymphadenopathy is commonly associated with parapneumonic effusion and that multiple sites may be involved. The degree of enlargement is moderate although lymphadenopathy of greater than 2 cm size should raise the possibility of other pathology.

Predictors of outcome and long-term survival in patients with pleural infection.

In pleural infection, medical treatment failure (chest-tube drainage and antibiotics) requires surgery and increases mortality. It would be helpful to predict which patients will fail this approach. We examined clinical predictors in 85 consecutive patients with pleural infection receiving chest drainage and intrapleural fibrinolytics, and recorded age, length of history, antibiotic delay and choice, time to drainage, blood/pleural fluid (PF) bacteriology, PF pH, lactate dehydrogenase (LDH), glucose and appearance, effusion size, pleural thickness on computed tomographic (CT) scan, and survival from time of drainage. Failures (surgery/death) were compared with successes. There were 13 (15%) medical failures. PF purulence was more frequent in medical failures (10 of 13 versus 29 of 72 successes, p < 0.02 chi-square). Absence of purulence was a useful predictor of success (positive predictive value [PPV] 93%). Purulence was not useful in predicting medical failure (PPV 26%). There was a trend for positive blood culture to predict failure (5 of 13 failures versus 11 of 72 successes, p = 0.05 chi-square), but no significant differences in other endpoints. Twelve (14%) patients died in follow-up, all with comorbidity within 400 d after drainage. Probability of survival at 4 yr was 86%. Of endpoints considered in this study, PF purulence was the only useful predictor of outcome with medical therapy in pleural infection. There is good long-term survival from pleural infection.

Acute severe asthma treated by mechanical ventilation: a comparison of the changing characteristics over a 17 yr period.

Recorded cases of asthma have increased in recent years. It is unclear, however, whether this apparent increase in prevalence is accompanied by an increase in severity of the disorder. One potential measure of asthma severity is the requirement for mechanical ventilation. This paper examines those patients ventilated for severe asthma in a district general hospital over a 17 yr period. Since the methods used to assess asthma attacks and the criteria for instituting mechanical ventilation in this hospital did not alter between 1973 and 1992 (Jones criteria), it was possible to compare directly characteristics of all ventilated patients during the study period. The comparison showed that there was a significant increase between the two study periods in the number of patients who required mechanical ventilation. Moreover, in the more recent period both the subjective speed of onset of the asthma attack and the objective time between admission and ventilation were significantly shorter. However, despite this increase in asthma severity the mortality and morbidity in the more recent study period were lower. Overall the results of this study support the view that, in the population served by our district general hospital, asthma has increased in severity. This increased severity is indicated by an increase in the number of patients requiring mechanical ventilation and in the rapidity with which attacks evolved. However, for patients in whom ventilation was required, improved care has lowered both morbidity and mortality.

Unravelling the helix--a physician's guide to spiral computed tomography.

The introduction of spiral technology to computed tomography (CT) scanners in the late 1980s has revolutionised the field of CT. Spiral CT offers definite practical benefits over conventional scanners and has expanded the role of CT through the development of new scanning techniques. CT scanning now rivals magnetic resonance imaging in many areas of investigation, and for some situations is the clear investigation of choice. This review is aimed at those clinicians who have access to spiral scanning services but wish to have a greater understanding of the technique and its clinical applications. The concept of spiral CT, and the differences between spiral and conventional scanning are discussed. The various clinical applications of the technique are illustrated.

CT scanning of the paranasal sinuses--the effect of reducing mAs.

High quality CT scans are required prior to fibreoptic endoscopic sinus surgery (FESS) surgery and in many institutions such scans are performed using a high mAs technique. Consequently, the investigation imparts a radiation dose to the patient and in particular to the eye. Such a radiation dose is a possible source of morbidity. We believe that the mAs, and consequently the radiation dose, can be considerably reduced without affecting scan quality. The present study compares the quality of sinus CT scans performed at two mAs values, 40 and 60. Scan quality was assessed in terms of the ability to visualize clearly important anatomical structures and in terms of overall perceived quality. We show that mAs values as low as 40 can be used without adversely affecting the diagnostic quality of the examination.

Pelvic musculoskeletal infection in infants -- diagnostic difficulties and radiological features.

Musculoskeletal infection involving the pelvis has rarely been reported in infants. When such infections involve the pelvic muscles they are generally believed to result from secondary spread from adjacent structures. We report five cases of primary pelvic musculoskeletal infection affecting infants <1 year, all of which presented during a 1-year period. In two patients the infection appeared to arise primarily in muscle. Clinical features were generally non-specific and often misleading, mimicking hip (4/5) or vascular (3/5) pathology; as a result, diagnosis was delayed in four patients. Radiological investigation was required to make the diagnosis and delineate the extent of the lesion in all cases. Magnetic resonance imaging (MRI) was the most useful imaging technique, accurately identifying the infection and its extent in all cases in which it was used. However, plain films, ultrasound (US), scintigraphy and computed tomography (CT) were all useful in individual cases and have a role in the primary investigation of these difficult infections. The clinical presentation of pelvic musculoskeletal infection in infants and the role of the various radiological investigations in its diagnosis is discussed.

Effect of ACTH on contralateral testicular damage and cytotoxic antisperm antibodies after unilateral testicular ischaemia in the rat.

Unilateral testicular ischaemia in the rat results in morphological damage in the contralateral testis (sympathetic orchiopathia). An increase in serum cytotoxic antisperm antibodies and serum IgM levels seen in this condition when compared to controls was reduced by daily i.m. administration of a synthetic adrenocorticotrophic hormone (ACTH) for 7 days. ACTH would appear to be acting as an immunosuppressant, possibly reducing the effect of this autoimmune condition on subsequent fertility.